THE AMERICAN LOBSTER. 
221 
extrusion. Anything which affects the vital condition of the adult female will thus 
affect the time of spawning. 
(18) The spawning season in the middle and eastern districts of Maine is about two 
weeks later than in Vineyard Sound. In 1893, 71 per cent of the eggs which were 
examined from the coast of Maine were extruded during the first half of August. 
(19) At Woods Hole, Massachusetts, 168 egg-bearing lobsters were captured from 
December 1, 1893, to June 30, 1894. Out of this number 44, or 25.6 per cent, bore eggs 
which had been laid outside of the summer months, chiefly in the fall. A lobster cap- 
tured at Matinicus Island, Maine, February 4, 1893, with the yolk uusegmented, and 
therefore in a very early stage, is mentioned in table 13, No. 20. Similar captures 
recorded in tables 12 and 13 sfiow that the laying of eggs in fall and winter is not rare. 
(20) Lobsters laid eggs in confinement only twice during the six summers which I 
spent at Woods Hole, although ripe females were frequently placed in the aquaria. 
When kept under these conditions, or even in floating-boxes outside, the eggs are 
usually not laid, but are absorbed directly from the ovary. 
(21) Law of production of eggs . — The law of the production of eggs may be 
expressed arithmetically as follows: The numbers of eggs produced at each reproductive 
period vary in a geometrical series , while the lengths of the lobsters producing these eggs 
vary in an arithmetical series. A lobster 8 inches long produces about 5,000 eggs. 
According to this law, a lobster 10 inches long would produce 10,000, a 12-inch lobster 
20,000, a 14-inch lobster 40,000. An examination of table 15, in which the number of 
eggs borne by over 4,000 lobsters is tabulated, shows that this law holds good up to 
the fourth term. When a lobster attains a length of 14 to 16 inches this high standard 
of production ceases to be maintained. A 17-inch lobster produces about 63,000 eggs. 
(22) The largest number of eggs recorded for a single lobster is 97,440. In one 
case the lobster was 15 inches long and in another 16 inches. In neither was the 
animal able to fold its tail on account of the large number of its eggs. This suggests 
that the rudimentary condition of the swimmerets on the first abdominal somite in the 
female is necessary for the protection of the eggs. The egg-bearing female goes about 
with the tail folded. This would be impossible if these appendages were of the usual 
size and carried the usual number of eggs. 
(23) The average weight of a 10^-inch female lobster with eggs is If pounds, the 
eggs weighing about 2 ounces. A 15-inch lobster, which weighs upward of 4 pounds, 
sometimes carries a burden of a pound of eggs.. The number of fresh eggs in a fiuid- 
ounce is about 6,440, and they weigh about 1 ounce avoirdupois. 
(24) Incubation period. — The period of incubation for the summer eggs at Woods 
Hole is from 10 to 11 months, in one case lasting 335 days, from July 1, 1890, to June 
1, 1891, when the young were just beginning to hatch out. 
(25) The general range of the hatching period of summer eggs at Woods Hole is 
from May 15 to July 15. The greater number are hatched in June. 
(26) The hatching of a single brood lasts in some cases over a week, owing to the 
slightly unequal rate of development of individual eggs. 
(27) The period of incubation of the summer eggs varies with the temperature of 
the water. In Newfoundland the hatching period is said to be from three to six weeks 
later than at Woods Hole (15th or 20tli of July to the 20th of August). 
(28) The hatching period also varies with the time of egg-laying. Thus the 
hatching of young lobsters has been observed in November in Newfoundland and 
Woods Hole, and in February at Gloucester, Massachusetts. 
